Coast Guard officials have yet to determine the cause of the “oily sheen” that appeared in Galveston Bay last week, but the cleanup has continued for several days and workers have still not identified the source. A three-quarter-mile-long sheen off the coast at Sixth St. in San Leon “was making some residents feel ill” when it appeared last Thursday, according to a report in the Galveston County Daily News. About 30 workers from Phoenix Pollution Control and Environmental Services were still cleaning up oily goo from a mile-long stretch of shoreline near April Fool Point at San Leon’s southern tip, a Coast Guard official told the Chronicle‘s Robert Stanton today. But the photo above, showing the slick on rocks at Bacliff — on the far northwestern side of the same peninsula — was sent to abc13 earlier today by a photographer who comments that workers didn’t want pictures taken. Another photo submitted by the same person appears to show boom deployed in the water off Grand Ave.: